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Effect of surface steps on chemical ordering in the subsurface of Cu(Au) solid solutions

Physical Review B 2021年第3期103卷 035401-035401页

作者： Kuo Liu Siming Zhang Dongxiang Wu Langli Luo Xianhu Sun Xiaobo Chen Dmitri Zakharov Shaobo Cheng Yimei Zhu Judith C. Yang Guofeng Wang Guangwen Zhou Department of Mechanical Engineering and Materials Science and Engineering Program State University of New York Binghamton New York 13902 USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Center for Functional Nanomaterials Brookhaven National Laboratory Upton New York 11973 USA Department of Condensed Matter Physics and Materials Science Brookhaven National Laboratory Upton New York 11973 USA Department of Chemical and Petroleum Engineering University of Pittsburgh Pittsburgh Pennsylvania 15261 USA

Atomic steps are typically assumed to only influence surface phenomena of solids. In contrast, here we show, using in situ atomic-resolution electron microscopy observations and atomistic modeling, the pronounced effect from surface steps in inducing compositional and structural evolution in the subsurface of a Cu(Au) solid solution. We find that Au surface segregation results in a stacked sequence of Cu-Au ordered phases in the subsurface. The presence of a monatomic step at the surface induces the formation of an antiphase boundary that extends from the surface step to deeper layers by maintaining the same composition profile associated with each terrace. The bunching of surface steps induces chemical disordering of the Cu-Au ordered phases in the subsurface region of the bunched steps. These results demonstrate the instant propagation of surface dynamics of atomic steps into the subsurface region and can find broader applicability in utilizing surface defects to tune the composition and structure in the subsurface of alloys.

关键词： Structural properties Surface & interfacial phenomena Alloys Density functional theory Electron microscopy

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Anomalous properties of spark plasma sintered boron nitride solids

arXiv

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arXiv 2024年

作者： Biswas, Abhijit Serles, Peter Alvarez, Gustavo A. Schimpf, Jesse Hache, Michel Kong, Jonathan Demingos, Pedro Guerra Yuan, Bo Pieshkov, Tymofii S. Li, Chenxi Puthirath, Anand B. Gao, Bin Gray, Tia Zhang, Xiang Murukeshan, Jishnu Vajtai, Robert Dai, Pengcheng Singh, Chandra Veer Howe, Jane Zou, Yu Martin, Lane W. Clancy, James Patrick Tian, Zhiting Filleter, Tobin Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Mechanical & Industrial Engineering University of Toronto 5 King’s College Road TorontoM5S 3G8 Canada Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Materials Science and Engineering University of California Berkeley United States Department of Materials Science and Engineering University of Toronto 184 College St TorontoM5S 3E4 Canada Department of Physics and Astronomy McMaster University HamiltonL8S 4M1 Canada Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory United States

Hexagonal boron nitride (h-BN) is brittle, however, its atomic-scale structural engineering can lead to unprecedented physical properties. Here we report the bulk synthesis of high-density crystalline h-BN solids by using high-temperature spark plasma sintering (SPS) of micron size h-BN powders. In addition to the high mechanical strength and ductile response of such materials, we have obtained anomalous values of dielectric constant beyond theoretical limits, high thermal conductivity, and exceptional neutron radiation shielding capability. Through exhaustive characterizations we reveal that SPS induces non-basal plane crystallinity, twisting of layers, and facilitates inter-grain fusion with a high degree of in-plane alignment across macroscale dimensions, resulting in near-theoretical density and anomalous properties. Our findings highlight the importance of material design, via new approaches such as twisting and interconnections between atomically thin layers, to create novel ceramics with properties that could go beyond their intrinsic theoretical predictions. © 2024, CC BY.

关键词： Spark plasma sintering

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Thin curved optics and the Twyman effect

Thin curved optics and the Twyman effect

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Optical Fabrication and Testing, OFT 2021 - Part of OSA Optical Design and Fabrication 2021

作者： Lakshmanan, Sanjay N. Lambropoulos, John C. Department of Mechanical Engineering University of Rochester RochesterNY14627 United States Materials Science Program University of Rochester RochesterNY14627 United States Laboratory for Laser Energetics University of Rochester RochesterNY14627 United States

We use numerical simulations and analytical techniques to assess the role of local thickness nonuniformity and curvature in the Twyman effect. A flat optic of similar thickness is used as a convenient metric for compa...

ISBN: (纸本)9781557528209

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Piezoelectric and triboelectric nanogenerators: Promising technologies for self-powered implantable biomedical devices

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Nano Energy 2024年 119卷

作者： Khan, Arshad Joshi, Ravindra Sharma, Manish Kumar Ganguly, Anindita Parashar, Parag Wang, Ting-Wei Lee, Sangmin Kao, Fu-Cheng Lin, Zong-Hong Department of Biomedical Engineering National Taiwan University Taipei10167 Taiwan International Intercollegiate PhD Program National Tsing Hua University Hsinchu30013 Taiwan Department of Power Mechanical Engineering National Tsing Hua University Hsinchu30013 Taiwan Department of Materials Science and Engineering National Tsing Hua University Hsinchu30013 Taiwan Internet of Senses Research Center National Tsing Hua University Hsinchu30013 Taiwan Department of Biomedical Engineering and Environmental Sciences National Tsing Hua University Hsinchu30013 Taiwan School of Mechanical Engineering Chung-Ang University Seoul06974 Korea Republic of Department of Orthopaedic Surgery Chang Gung Memorial Hospital Taoyuan33305 Taiwan College of Medicine Chang Gung University Taoyuan33302 Taiwan Department of Chemical Engineering National Taiwan University Taipei10167 Taiwan

Implantable biomedical devices (IBDs) have garnered wide-scale attention in recent years due to their enormous contribution to the biomedical sector. However, an uninterrupted and reliable power source has consistently been the primary barrier for IBDs, which is greatly alleviated by batteries. The widespread application of battery-powered IBDs is hindered by several limitations, including bulkiness, limited capacity and shelf-life, and expenditure associated with surgery-based battery recharge/replacement. To address these challenges, state-of-the-art self-powering technologies have emerged, including implantable piezoelectric nanogenerators (iPENGs) and implantable triboelectric nanogenerators (iTENGs). These technologies enable IBDs to operate autonomously by harnessing the minute mechanical movements of internal organs, such as heartbeat, respiration, blood circulation, muscle contraction/relaxation, and lung vibration. This review focuses on the recent advancements in iTENGs and iPENGs for the development of self-powered IBDs with a wide range of applications, including energy harvesting from biomechanical and ultrasound sources and energy storage using batteries and capacitors. This study also explores the extensive sensing applications of IBDs in various areas including cardiac, gastrointestinal, bladder, and ligament-strain monitoring. Finally, therapeutic applications of IBDs, such as nerve stimulation, bone stimulation, cartilage therapy, tissue regeneration, muscle stimulation, drug delivery, and diabetes management are discussed. © 2023 Elsevier Ltd

关键词： Nanogenerators

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Electron-phonon scattering governs both ultrafast and precessional magnetization dynamics in Co-Fe alloys

arXiv

引用

arXiv 2021年

作者： Mohan, Ramya Ortiz, Victor H. Vuong, Luat Coh, Sinisa Wilson, Richard B. Materials Science & Engineering Program University of California Riverside United States Department of Mechanical Engineering University of California Riverside United States

Recent investigations have advanced the understanding of how structure-property relationships in ferromagnetic metal alloys affect the magnetization dynamics on nanosecond time-scales. A similar understanding for magnetization dynamics on femto- to pico-second time-scales does not yet exist. To address this, we perform time-resolved magneto optic Kerr effect (TRMOKE) measurements of magnetization dynamics in Co-Fe alloys on femto- to nano-second regimes. We show that Co-Fe compositions that exhibit low Gilbert damping parameters also feature prolonged ultrafast demagnetization upon photoexcitation. We analyze our experimental TRMOKE data with the three-temperature-model (3TM) and the Landau-Lifshitz-Gilbert equation. These analyses reveal a strong compositional dependence of the dynamics across all time-scales on the strength of electron-phonon interactions. Our findings are beneficial to the spintronics and magnonics community, and will aid in the quest for energy-efficient magnetic storage applications. © 2021, CC BY.

关键词： Cobalt alloys

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Spin scattering and Hall effects in monolayer Fe3GeTe2

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Physical Review B 2023年第13期108卷 134425-134425页

作者： Luyan Yu Jie-Xiang Yu Jiadong Zang Roger K. Lake Houlong Zhuang Gen Yin Department of Physics University of Texas at Austin Austin Texas 78712 USA Department of Physics University of Florida Gainesville Florida 32611 USA Department of Physics and Materials Science Program University of New Hampshire Durham New Hampshire 03824 USA Laboratory for Terahertz and Terascale Electronics (LATTE) Department of Electrical and Computer Engineering University of California at Riverside Riverside California 92521 USA Mechanical and Aerospace Engineering Arizona State University Tempe Arizona 85287 USA Department of Physics Georgetown University Washington DC 20057 USA

We theoretically show that the carrier transport in a monolayer Fe3GeTe2 experiences a transition between anomalous and spin Hall effects when the spin polarization of disorders switches between out-of-plane and in-plane. These Hall effects are allowed when the magnetization is polarized in-plane, breaking the C3 rotation symmetry. The transition originates from the selection rule of spin scattering, the strong spin-orbit coupling, and the van Hove singularities near the Fermi surface. The scattering selection rule tolerates the sign change of the disorder spin, which provides a convenient method to detect the switching of antiferromagnetic insulators regardless of the interfacial roughness in a heterostructure. This provides a convenient platform for the study of 2D spintronics through various van der Waals heterostructures.

关键词： Magnetotransport Spin Hall effect 2-dimensional systems Density functional calculations

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Influence of Temperature and Stress State on the Twip Behavior of 201ln and 316lv Austenitic Stainless Steels

SSRN

引用

SSRN 2022年

作者： Braga, Diogo Pedrino Corrêa, Leonardo Muthi Sordi, Vitor Luiz Rovere, Carlos Alberto Della Cintho, Osvaldo Mitsuyuki Kliauga, Andrea Madeira Federal University of São Carlos Graduate Program in Materials Science and Engineering São Carlos São Paulo Brazil Federal University of São Carlos Graduate Program in Mechanical Engineering São Carlos São Paulo Brazil Federal University of São Carlos Department of Materials Engineering São Carlos São Paulo Brazil State University of Ponta Grossa Department of Materials Engineering Ponta Grossa Paraná Brazil

The present results analyzed deformation behavior under tension and compression of two different austenitic stainless steels: AISI 201LN, with low nickel content and stabilized with Mn and N;and AISI 316LV, stabilized with Ni and with low content of interstitial atoms. mechanical tests were performed at 10 -3 s -1 and at temperatures varying from -100 to 600 o C to yield comparable values of the stacking fault energy (SFE). The resulting microstructure was analyzed by X-ray diffraction and EBSD. The stress-strain curves were analyzed using the Kocks-Mecking (K-M) approach. For comparable stacking fault energies, temperature enhances the thermal activation effects that led to lower fraction of mechanical twins in the 201LN compared with the 316LV. The crystallographic re-orientation followed the flow rule irrespective of the temperature and deformation mechanism: tension and compression experiments showed the or orientation with the tension axis, respectively. In tension the dislocation storage and recovery factors of the K-M model were larger than in the compression and the amount of stored dislocations and crystallite size reflect these effects. In the compression, the TWIP effect was reduced for the 316LV and suppressed for the 201LN. © 2022, The Authors. All rights reserved.

关键词： Stacking faults

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aflow++: A C++ framework for autonomous materials design

引用

Computational materials science 2023年 217卷

作者： Oses, Corey Esters, Marco Hicks, David Divilov, Simon Eckert, Hagen Friedrich, Rico Mehl, Michael J. Smolyanyuk, Andriy Campilongo, Xiomara van de Walle, Axel Schroers, Jan Kusne, A. Gilad Takeuchi, Ichiro Zurek, Eva Nardelli, Marco Buongiorno Fornari, Marco Lederer, Yoav Levy, Ohad Toher, Cormac Curtarolo, Stefano Department of Mechanical Engineering and Materials Science Duke University DurhamNC27708 United States Center for Autonomous Materials Design Duke University DurhamNC27708 United States LIFT American Lightweight Materials Manufacturing Innovation Institute DetroitMI48216 United States Institute of Ion Beam Physics and Materials Research Helmholtz-Zentrum Dresden-Rossendorf Dresden01328 Germany Theoretical Chemistry Technische Universität Dresden Dresden01062 Germany Institute of Solid State Physics Technische Universität Wien WienA-1040 Austria School of Engineering Brown University ProvidenceRI02912 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06511 United States Materials Measurement Science Division National Institute of Standards and Technology GaithersburgMD20899 United States Department of Materials Science and Engineering University of Maryland College Park MD20742 United States Department of Chemistry State University of New York at Buffalo BuffaloNY14260 United States Department of Physics and Department of Chemistry University of North Texas DentonTX76203 United States Santa Fe Institute Santa FeNM87501 United States Department of Physics and Science of Advanced Materials Program Central Michigan University Mount PleasantMI48859 United States Department of Physics NRCN Beer-Sheva84190 Israel Department of Materials Science and Engineering and Department of Chemistry and Biochemistry University of Texas at Dallas RichardsonTX75080 United States

The realization of novel technological opportunities given by computational and autonomous materials design requires efficient and effective frameworks. For more than two decades, aflow++ (Automatic-Flow Framework for materials Discovery) has provided an interconnected collection of algorithms and workflows to address this challenge. This article contains an overview of the software and some of its most heavily-used functionalities, including algorithmic details, standards, and examples. Key thrusts are highlighted: the calculation of structural, electronic, thermodynamic, and thermomechanical properties in addition to the modeling of complex materials, such as high-entropy ceramics and bulk metallic glasses. The aflow++ software prioritizes interoperability, minimizing the number of independent parameters and tolerances. It ensures consistency of results across property sets — facilitating machine learning studies. The software also features various validation schemes, offering real-time quality assurance for data generated in a high-throughput fashion. Altogether, these considerations contribute to the development of large and reliable materials databases that can ultimately deliver future materials systems. © 2022

关键词： Machine learning

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A novel four-field mixed variational approach to Kirchhoff rods implemented with finite element exterior calculus

arXiv

引用

arXiv 2022年

作者： Jamun Kumar, N. Dhas, Bensingh Srinivasa, Arun R. Reddy, J.N. Roy, Debasish Centre Of Excellence In Advanced Mechanics Of Materials Indian Institute Of Science Bangalore India J. Mike Walker'66 Department Of Mechanical Engineering Texas A&M University College StationTX77843-3123 United States

A four-field mixed variational principle is proposed for large deformation analysis of Kirchhoff rods with the lowest order C0mixed FE approximations. The core idea behind the approach is to introduce a one-parameter family of points (the centerline) and a separate one-parameter family of orthonormal frames (the Cartan moving frame) that are specified independently. The curvature and torsion of the curve are then related to the relative rotation of neighboring frames. The relationship between the frame and the centerline is then enforced at the solution step using a Lagrange multiplier (which plays the role of section force). Well known frames like the Frenet-Serret are defined only using the centerline, which demands higher-order smoothness for the centerline approximation. Decoupling the frame from the position vector of the base curve leads to a description of torsion and curvature that is independent of the position information, thus allowing for simpler interpolations. This approach is then cast in the language of exterior calculus. In this framework, the strain energy may be interpreted as a differential form leading to the natural force-displacement (velocity) pairing. The four-field mixed variational principle we propose has frame, differential forms, and position vector as input arguments. While the position vector is interpolated linearly, the frames are interpolated as piecewise geodesics on the rotation group. Similarly, consistent interpolation schemes are also adopted to obtain finite dimensional approximations for the differential forms appearing in the mixed functional. Using these discrete approximations, a discrete mixed variational principle is laid out which is then numerically extremized. The discrete approximation is then applied to a few benchmark problems. Vis-á-vis most available approaches, our numerical studies reveal an impressive performance of the proposed method without numerical instabilities or locking. © 2022, CC BY.

关键词： Torsional stress

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Preprocessing Techniques for Enhancing Vision-Based Detection System for Tire Sidewall Extraction

Preprocessing Techniques for Enhancing Vision-Based Detectio...

引用

International Seminar on Research of Information Technology and Intelligent Systems (ISRITI)

作者： Jia Hao Loo Veronica Lestari Jauw Chin Seong Lim Khairul-Rijal Sarmin Nunung Nurul Qomariyah Ahmad Nurul Fajar Department of Mechanical Materials and Manufacturing Engineering University of Nottingham Malaysia Malaysia Continental Tyre Technology Centre Malaysia Petaling Jaya Malaysia Computer Science Department School of Computing and Creative Arts Bina Nusantara University Jakarta Indonesia Information System Management Department BINUS Graduate Program-Master Information Systems Bina Nusantara University Jakarta Indonesia

ISBN: (数字)9798331519643

ISBN: (纸本)9798331519650

This study aims to develop a system for extracting crucial information from tire sidewalls using Optical Character Recognition (OCR). Initially, images of tire were captured manually by smartphone cameras, including Redmi 9T, iPhone 11, and Galaxy S23 Ultra. The captured images are then transferred to a computer for storage. Subsequently, these images were cropped according to the boundaries identified by Hough Circle Transform (HCT). The cropped images were then further pre-processed. During the pre-processing phase, geometrical transformation and image sharpening techniques are applied to enhance the clarity and readability of the text images. The text is then extracted using Google Vision, with the extracted text categorized by size, DOT, brand and pattern. The results indicated that the effectiveness of image pre-processing was constrained by the accuracy of circle detection, which reached a maximum rate of 87.1%. This causes parts of the text to be cut out inaccurately, leading to a suboptimal extraction accuracy of 55.65%. It is also observed that the Redmi 9T camera produced inconsistent results compared to other devices. Specifically, the iPhone 11 and Samsung Galaxy S23 Ultra demonstrated superior extraction accuracies of 69.71% and 66.37%, respectively, whereas the Redmi 9T achieved a lower extraction accuracy of 37.76%.

关键词： Accuracy Optical character recognition Text categorization Lighting Transforms US department of Transportation Cameras Tires Internet Data mining

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